Flangeless pipe joint and a process for manufacturing such a joint

ABSTRACT

A flangeless pipe joint for polymer-lined piping in which the piping is joined by a coupling and the lining is slip, loose, interference or swaged fitted into the pipes and joined at the ends thereof against relative movement.

The subject invention pertains to a flangeless pipe joint. The subjectinvention further pertains to a process for manufacturing a flangelesspipe joint.

Currently available and well known plastic-lined piping productscomprise a family of pipes, fittings, and valves especially designed forhandling corrosive or high purity liquids. Such products generallycomprise steel lined with a polymeric material. Such materials include,but are not limited to polyvinylidene chloride, polypropylene,polyvinylidene fluoride, perfluoroalkoxy copolymer, fluorinatedethylene-propylene copolymer, ethylene trifluoroethylene,ethylchlorotrifluoroethylene, and polytetrafluoroethylene. Such productsenjoy both the structural integrity of steel and the high chemicalresistance characteristic of the selected polymeric liner.

Typically, each pipe, fitting, valve, etc. will typically contain aflange at or substantially near each end thereof. Adjacent pipes,fittings, valves, etc., within a given pipeline may be joined one toanother by the fastening together of such flanges, e.g., by bolting.

While flanged joints are acceptable in most applications, advantagecould be had in flangeless joints. Such joints could be constructed tobe fluid-proof and vapor-proof, to decrease (if not eliminate) fugitiveemissions through the joints. Moreover, such joints would be less bulkythan flanged joints, which would make their enclosure within secondarycontainment systems less unwieldy

U.S. Pat. No. 4,780,163 provides a method of sliplining pipe to form apipeline having flangeless joints. In particular, a section of pipe iscut to form two pieces and a cutout portion, such that the point of thecut forms a closure point. Polymeric liner segments are then drawnthrough each of the two pieces and extend beyond the ends of the pipe tothe closure point. Then, the liner segments are fused at the closurepoint, the liner segments are insulated at the point of fusion, and thecut out portion is welded to the pieces to form a continuous piece ofpipe. The patent requires that a heat shield-insulation material bewrapped around the fused liner segments between the fused liner segmentsand the cutout portion of the pipe Such heat shield-insulation materialmay be used due to the relatively large gap that exists between theouter surface of the liner and the inner surface of the pipe segment,characteristic of sliplined pipe.

U.S. Pat. No. 5,127,116 discloses a joint for pipes, each of whichcontains a polyolefin liner, comprising two pipe end portions spacedapart with their liners protruding from the end portions and joined byjoining means (such as electrofusion), a shell interconnecting the pipeend portions, and grout in the space between the liners and the shell.The disclosed joint is disadvantageous, in that the necessity of groutincreases the bulk of the joint. The disclosed joint is furtherdisadvantageous, it that is does not have leakage detectioncapabilities. The disclosed joint is further disadvantageous, in that itdoes not provide a system wherein the liner is retained between thefirst and second sections of pipe at the point of the joining means in amanner which restrains linear movement of the liners.

Industry would find advantage in flangeless joints for plastic-linedpipe systems. In particular, the industry would find advantage inflangeless joints for plastic-lined pipe systems, wherein adjacentliners are joined together by joining means other than compressiveforce, such as to form a fluid- and vapor-tight seal between adjacentliners. Industry would further find advantage in a flangeless joint,wherein the linear movement of a polymeric liners is restrained, such asduring thermal cycling. Industry would further find advantage in aflangeless joint equipped with a secondarily contained leak detectionzone for detecting leaks in the joining means.

Accordingly, the subject invention provides a flangeless pipe joint forpolymer-lined pipe comprising:

(a) a first section of pipe having a first section end, said firstsection of pipe being lined with a first polymeric liner having a firstliner end extending from said first section end;

(b) a second section of pipe having a second section end, said secondsection of pipe being lined with a second polymeric liner having asecond liner end extending from said second section end,

(c) joining means for joining the first liner end to the second linerend; and

(d) an annular coupling for joining said first section end and saidsecond section end by means other than welding or bolting.

The subject invention further provides a process for preparing aflangeless pipe joint for polymer-lined pipe comprising:

(a) providing a first section of pipe lined with a first polymeric linerhaving a first liner end and a second section of pipe lined with asecond polymeric liner having a second liner end;

(b) removing a portion of said first section to expose a portion of saidfirst polymeric liner and to form a modified first section having afirst section end,

(c) removing a portion of said second section to expose a portion ofsaid second polymeric liner and to form a modified second section havinga second section end;

(d) joining said first liner end and said second liner end; and

(e) providing an annular coupling to join said first section end andsaid second section end by means other than welding or bolting.

In a particularly preferred embodiment, the flangeless joint and theprocess of the subject invention will create a void between the meansfor joining the first and second liner ends and the coupling, whereuponleakage detection capabilities are created. In another particularlypreferred embodiment, the flangeless joint and the process of thesubject invention will create a "locked-in" system, wherein the theliner is retained between the first and second sections of pipe at thepoint of the joining means in a manner which restrains linear movementof the liners.

These and other features of the invention will be more fully set forthin the following detailed description wherein:

FIG. 1 is a sectional view of a first flangeless polymer-lined pipejoint of the subject invention;

FIG. 2 is a sectional view of a second flangeless polymer-lined pipejoint of the subject invention; and

FIG. 3 is a sectional view of a third flangeless polymer-lined pipejoint of the subject invention, wherein common reference numerals referto common components.

Plastic-lined pipe typically falls into one of two categories: transferpipe and process pipe. Transfer pipe refers to pipe typically locatedbeneath the ground for the transfer of a material long distances, fromone location to another. Transfer pipe is typically prepared by sliplining, wherein a polymeric liner is pulled through an installed pipeand retained within such pipe only at the points of joinder betweenadjacent pipe segments, each pipe segment being hundreds of feet long.Typically, the outside diameter of the liner is up to about 10 percentless than the inside diameter of the pipe segments, causing asignificant gap between the liner and the inner wall of the pipe. Astransfer pipe is not typically subjected to thermal cycling conditionsand to the extent that high line pressures compress the liner againstthe inner wall of the pipe, the relatively large gap between the linerand the inner wall of the pipe is not problematic.

Plastic-lined process pipe typically falls into one of threesubcategories: loose-lined pipe, interference fit pipe, and swaged pipe.In contrast to transfer pipe, process pipe typically comprises shorterpipe segments, on the order of about forty feet and less. Further,process pipe is typically characterized by an outside liner diameterwhich is at least about 97 percent of the inside diameter of the pipesegments.

Loose-lined pipe is characterized by a polymeric liner retained within apipe only at the points of joinder between adjacent pipe segments,wherein the outside liner diameter is at least about 97 percent of theinside diameter of the pipe segment. Loose-lined pipes are typicallymanufactured by slipping a pre-formed polymeric liner into a flangedpipe segment, flaring the liner over the structurally rigid flange face,and bolting the flange to an adjacent flange. In loose-lined pipe, theliner is thus retained within the pipe segment by the compressive forceexerted on the flared portion of the liner at the flange face.Loose-lined pipe is generally sold as its components, e.g., as pipesegments, polymeric liners, and flanges. In the field, the liner may beinserted into the flanged pipe segment, and may be flared as describedabove. Suppliers for loose-lined pipe components includeCrane-Resistoflex Co. (Marion, N.C.), and Performance Plastic Products(Houston, Tex.).

Interference fit pipe, which is also known as reverse swaged pipe, ischaracterized by a zero tolerance fit between the polymeric liner andthe pipe segments. Interference fit plastic-lined pipe is typicallyformed by compressing a preformed polymeric liner having an outerdiameter greater than the inner diameter of the pipe segment by passingit through a sizing die, and inserting the compressed liner into thepipe segment before the liner expands. Upon the release of the force bywhich the liner is pulled through the pipe, the memory of the plasticcauses the liner to exert force upon the inner wall of the pipe segment,serving to assist in retaining the liner within the pipe segment. Due tothe special apparatus required to achieve the interference fitrelationship, interference fit pipe is generally available as pre-linedpipe segments. Interference fit pipe is sold by Crane-Resistoflex Co.(Marion, N.C.) as Thermal Locked pipe.

Swaged pipe is characterized by a zero tolerance fit between thepolymeric liner and the pipe segments. Swaged pipe is typically formedby inserting a preformed polymeric liner into an oversized pipe segmentand physically compressing both the pipe and the liner under tremendouspressure such that the liner and the pipe segment are reduced in size tothe finished diameters. To further facilitate retention of the linerwithin the pipe segment, pipe segments to be lined may be "picked" toprovide barbs and recessed portions into which the liner is directedduring swaging. Due to the special apparatus required to swage pipe,swaged pipe is generally available as pre-lined pipe segments. Swagedpipe is sold by The Dow Chemical Company (Midland, Mich.).

Metal and polymers have different rates of expansion under heat. Swagedpipe, and to some extent interference fit pipe, is advantageous ascompared to loose-lined pipe when temperature changes within the pipingor when extreme ambient temperatures are encountered. Zero tolerance fitpiping systems tend to better retain the liner in close proximity withthe metal, thus limiting the extent of expansion and retraction of theliner during temperature cycling. This is particularly true in the caseof swaged pipe having the "picked" surface described above, wherein theresultant inner locking secures the liner to the steel pipe segment overthe entire length of the pipe segment, thereby evenly distributing thestresses caused by thermal expansion and contraction.

The subject invention provides a flangeless polymer-lined pipe jointuseful to join adjacent sections of polymer-lined transfer or processpipe.

In a first embodiment, the subject invention pertains to a flangelesspipe joint, such is as depicted in FIG. 1. As depicted in FIG. 1, firstsection of pipe 100 and second section of pipe 100' are lined with firstpolymeric liner 110 and second polymeric liner 110', respectively. Firstsection of pipe 100 has a first section end 120, while second section ofpipe 100' has a second section end 120'. First polymeric liner 110 has afirst liner end 130, while second polymeric liner 110' has a secondliner end 130'. First liner end 130 and second liner end 130' are joinedby joining means 140, e.g., a butt fusion or infrared weld, to form ahigh-integrity pipe joint seal. Coupling 150 connects first section end120 and second section end 120'. In this embodiment, coupling 150comprises fitting body 160 and swage rings 170 and 170' which serve tosecure fitting body 160 to first section of pipe 100 and second sectionof pipe 100' through compressive force. Secure retention of coupling 150onto first section of pipe 100 and second section of pipe 100' isfacilitated by circumferential sealing lands 180 and 180', which, uponhydraulic advancement of swage rings 170 and 170' press into firstsection of pipe 100 and second section pipe 100'. In this embodiment,annular gap 175 exists between fitting body 160 and first liner 120 andsecond liner 120' at joining means 140. Annular gap 175 provides theflangeless joint with a secondarily contained leak detection zone. Bore190 connects annular gap 175 with a suitable leak detection device, notshown. In particular, wire leads could be inserted from the leakagedetection device, through bore 190, into annular gap 175. To restrainlinear movement of first and second polymeric liners 110 and 110', aportion of joining means 140, e.g., a weld bead, extends into annulargap 175. The depicted coupling 150, without bore 190, is commerciallyavailable from Lokring Corporation (Foster City, Calif.).

In another embodiment, the subject invention pertains to a process forpreparing the flangeless pipe joint depicted in FIG. 1. In such anembodiment, first section of pipe 100 and second section of pipe 100'are lined with first polymeric liner 110 and second polymeric liner110', respectively. A portion of first section of pipe 100 and of secondsection of pipe 100' are removed, e.g., by either machining away suchportions or by cutting and removing the metal portions, leaving firstpolymeric liner 110 and second polymeric liner 110' intact. The removalof such portions results in the exposure of first section end 120 andsecond section end 120'. First liner end 130 and second liner end 130'are joined by joining means 140, e.g., by butt fusion welding, to form ahigh-integrity pipe joint seal. Preferably, joining means will be suchas to form a weld bead large enough to restrain linear movement of firstand second polymeric liners 110 and 110'. First section of pipe 100 andsecond section of pipe 100' are inserted into fitting body 160 ofcoupling 150. A hydraulic tool advances swage rings 170 and 170' axiallyover fitting body 160. Simultaneously, swage rings 170 and 170' compressfitting body 160 down onto first section of pipe 100 and second sectionof pipe 100', causing circumferential sealing lands 180 and 180'machined in fitting body 160 to further press into first section of pipe100 and second section pipe 100', and thus to further promote secureretention of coupling 160 thereupon. Bore 190 is provided by standardmetalworking techniques and extends through fitting body 160 intoannular gap 175. Such drilling may occur prior to insertion of firstsection of pipe 100 and second section of pipe 100' onto coupling 150,or after swage rings 170 and 170' are advanced over fitting body 160. Toavoid accidental damage to first polymeric liner 110 and secondpolymeric liner 110', drilling of bore 190 will preferably occur priorto insertion of first section of pipe 100 and second section of pipe100'.

In another embodiment, the subject invention pertains to a flangelesspipe joint, such is as depicted in FIG. 2, and to a process for itspreparation. The embodiment of FIG. 2 is similar to that depicted inFIG. 1, excepting that an alternate means for joining first polymericliner 110 and second polymeric liner 110' is employed. In particular,the joining means of FIG. 2 utilizes a polymeric coupling 185. Polymericcoupling 185 has a first annular portion 190 and a second annularportion 195. First annular portion preferably has a configurationwhereupon the inner and outer diameters are approximately equal to theinner and outer diameters of first and second sections of pipe 100 and100'. Second annular portion preferably has an inner diameter greaterthan or equal to the inner diameter of first polymeric liner 110 andsecond polymeric liner 110'. Preferably, the inner diameter of secondannular portion 190 will equal the inner diameters of first and secondpolymeric liners 110 and 110'. First polymeric liner 110 and secondpolymeric liner 110' are inserted into the respective sides of firstannular portion 190, such that the first liner end 130 and second linerend 130' abut against second annular portion 195. Polymeric coupling 185is joined to first and second polymeric liners 110 and 110' by suitablejoinder means, such as socket welding, adhesives, solvent welding, orelectrofusion. Annular gaps 196 and 196' are provided as secondarilycontained leak detection zones. To restrain linear movement of firstpolymeric liner 110 and second polymeric liner 110', e.g., duringthermal cycling, lands 197 and 197' are provided. Annular gaps 196 and196' and lands 197 and 197' are produced by chamfering first and secondsections of pipe 100 and 100' prior to insertion of the first and secondpolymeric liners 110 and 110' into polymeric coupling 185. In apreferred embodiment, polymeric coupling 185 will be molded into fittingbody 160. First and second sections of pipe are then inserted intocoupling 185 as retained within fitting body 160, polymeric liners 110and 110' are joined, and swage rings 170 and 170' are thereaftercompressed to form the completed joint. Optionally, fitting body 160will be provided with internal annular grooves 199, such that theplastic of polymer coupling 185 fills such grooves during molding.Through bores are provided in fitting body 160, and in swage rings 170and 170', such that, upon hydraulic advancement of swage rings 170 and170' onto fitting body 160, the bores align to form bores 198 and 198'which permit communication between a leakage detection device (notshown) and annular gaps 196 and 196', respectively.

In another embodiment, the subject invention pertains to a flangelesspipe joint, such is as depicted in FIG. 3. As depicted in FIG. 3, firstsection of pipe 200 and second section of pipe 200' are lined with firstpolymeric liner 210 and second polymeric liner 210', respectively. Firstsection of pipe 200 has a first section end 220, while second section ofpipe 200' has a second section end 220'. First polymeric liner 210 hasan optionally beveled first liner end 230, while second polymeric liner210' has an optionally beveled second liner end 230'. First liner end230 and second liner end 230' are joined by joining means 240, e.g., afillet weld, to form a high-integrity pipe joint seal. Coupling 250connects first section end 220 and second section end 220'. Coupling 250comprises a housing 255. Housing 255 is equipped with pockets 260 and260'. Retained within pockets 260 and 260' are polymeric or elastomericseals 265 and 265', respectively. Housing 255 is compressed onto firstsection of pipe 200 and second section of pipe 200', whereupon first andsecond sections of pipe 200 and 200' and first and second polymericliners 210 and 210' are likewise compressed in annular regions 270 and270', to promote secure retention of coupling 250 on first section 200and second section 200'. During such compression, pockets 260 and 260'are likewise compressed, whereupon seals 265 and 265' are compressed toform a fluid-tight seal. In this embodiment, annular gap 275 existsbetween housing 255 and first liner 220 and second liner 220' at joiningmeans 240, which creates a secondarily contained leak detection zone.Bore 280 connects annular gap 275 with a suitable leakage detectiondevice, not shown. Couplings 250, without bore 280, are commerciallyavailable from Deutsch Metal Components (Gardena, Calif.), such as thecoupling having the tradename PYPLOK. As depicted in the preferredembodiment of the FIGURE, joining means 240 are such that the outerdiameter of first and second polymeric liners 210 and 210', at the pointof joining means 240, are greater than the outer diameter of first andsecond polymeric liners throughout the remainder of their length. Suchan expanded fillet weld serves to limit linear movement of the first andsecond polymeric liners, which becomes important in applicationscharacterized by thermal cycling.

In another embodiment, the subject invention pertains to a process forpreparing the flangeless pipe joint depicted in FIG. 3. In such anembodiment, first section of pipe 200 and second section of pipe 200'are lined with first polymeric liner 210 and second polymeric liner210', respectively. A portion of first section of pipe 200 and of secondsection of pipe 200' are removed, e.g., by either machining away suchportions or by cutting and removing the metal portions, leaving firstpolymeric liner 210 and second polymeric liner 210' intact. The removalof such portions results in the exposure of first section end 220 andsecond section end 220'. First polymeric liner 210 and second polymericliner 220 are optionally beveled to form first liner end 230 and secondliner end 230'. Such beveling is preferred when the polymeric liners areto be joined via fillet welding. First liner end 230 and second linerend 230' are joined by joining means 240, e.g., a fillet weld, to form ahigh-integrity pipe joint seal. Such a fillet weld is formed by meltinga rod of plastic such that the plastic flows into the beveled channelformed between first liner end 230 and second liner end 230'. Housing255 of coupling 250 is slid over first section of pipe 200 and secondsection of pipe 200'. A hydraulic tool circumferentially andsequentially compresses housing 255 over first section of pipe 200 andsecond section of pipe 200'. During such compression, housing 255 iscompressed onto first section of pipe 200 and second section of pipe200', whereupon first and second sections of pipe 200 and 200' and firstand second polymeric liners 210 and 210' are likewise compressed inannular regions 270 and 270' to promote secure retention of coupling 250on first section 200 and second section 200'. During such compression,pockets 260 and 260' are likewise compressed, whereupon seals 265 and265' are compressed to form a fluid-tight seal. Bore 280 is drilledthrough housing 255 into annular gap 275. Such drilling may occur priorto insertion of first section of pipe 200 and second section of pipe200' into coupling 250, or after compression of housing 255 onto firstand second sections of pipe 200 and 200'.

Additional couplings will be suitable to join the first and secondsections of pipe. For instance, a coupling available from Advanced MetalComponents, Inc. (Menlo Park, Calif.), having the tradename CRYOFIT, maylikewise be employed. Such couplings are cylindrical in configuration,and have raised circumferential ridges formed within the bore of thecoupling. Such couplings are fabricated of a nickel/titanium alloy andhave been machined with an inner diameter approximately three percentless than the outer diameter of the first and second sections of pipe tobe joined. Upon insertion into liquid nitrogen, at a temperature of-325° F. (-195° C.), the alloy is rendered ductile. A sizing mandrel ishydraulically pushed through the bore of the coupling to result in acoupling having an inner diameter approximately five percent larger thanthe outer diameter of the first and second sections of pipe to bejoined. The coupling is removed from the liquid nitrogen, and is slidinto place over the pipe segments at the point at which the first andsecond polymeric liners have been previously joined. As the temperatureof the coupling increases, the coupling contracts in a radially inwardmanner, applying great pressure to the first and second sections ofpipe, causing the coupling, and, in particular, the raisedcircumferential ridges of the coupling, to press into the first andsecond sections of pipe, bulging the metal and liner of the pipesections radially inwardly.

As depicted in the above FIGURES, and in accordance with means known inthe art, adjacent polymeric liner ends are joined. Such means include,but are not limited to, e.g., butt fusion welds, infrared welds, filletwelds, socket welds, solvent welds, ultrasonic welds, vibratory welds,electrofusion, and adhesives. Depending upon the type of joinder meansemployed, it may be advantageous to trim the liner ends to form moreuniform joining surfaces and/or to reduce the degree to which the linerextends past the end of the first or second section end.

One particularly preferred joining means is butt fusion welding. Asuitable apparatus for butt fusion welding adjacent polymeric liners isdescribed in U.S. Pat. No. 4,352,708, the relevant portions of which areincorporated herein by reference. Another suitable apparatus for buttfusion welding adjacent polymeric liners is available from Omicron,S.N.C (Caselle Di Selvazzano, Italy).

In an exemplary butt fusion welding process for polyvinylidene fluorideliners, adjacent liner ends are pressed against a hot plate at atemperature of 210° C. with a combined pressure of 10 psi (70kilopascals) until a 1/32 inch (0.08 cm) bead forms on the outercircumference of the joint. The pressure is then reduced to 1 psi (6kilopascals) for an additional 45 seconds. Then, the plate is removed bybacking the adjacent liner ends away and pulling out the plate. The twoheated partially melted adjacent liner ends are quickly pushed togetherat a pressure of 10 psi (70 kilopascals) and held together at thatpressure for 20 minutes.

Another particularly preferred joining means is infrared welding.Infrared welding differs from butt fusion welding in that in the former,heat is transferred to the adjacent polymeric liner ends by radiationonly. Such joining means are particularly applicable to fluoropolymers,such as perfluoroalkoxy copolymer, which may be adversely affected bydirect contact with a hot plate, as employed in conventional butt fusionwelding. One supplier of infrared welding equipment is Georg FisherPiping Systems (Schaffhausen, Switzerland).

Another particularly preferred joining means is fillet welding, whereina thermoplastic filler rod is heated and the flowing material is appliedto the liner ends to join them. Optionally, the liner ends will bebeveled such that when they are brought together, a V-shaped annularchannel is formed, the point of the V lying at the inner surface of theliner at the point of joinder. The fillet weld will be made within the Valong the bevels, such that the weld bead contacts more surface area ofthe liner ends than if the filler rod was merely passed over the outercircumference of straight-cut liner ends.

Another particularly preferred joining means is electrofusion, wherein apolymeric coupling, such as is depicted in FIG. 2 is employed. In suchan embodiment, the polymeric coupling is equipped with a heatingelement, by which is can be heated and caused to fuse itself and thefirst and second polymeric liners to which it bonds.

While the subject invention has been described in terms of plastic-linedpipe segments, it will be recognized that the invention further appliesto injection molded pipe fittings, such as ells, tees, wyes, etc. Inthis case, the term "first section of pipe" and/or "second section ofpipe" will include linear sections of pipe, as well as, e.g., fittings.Due to their typically nonlinear configurations, fittings are typicallyformed by turning individual units and joining the turned units to formthe desired configuration, e.g., by welding. Thus, two units are joinedto form elbows, three units are joined to form both tees and wyes, andfour units are joined to form crosses. Once joined, one or more dies areinserted into the fitting. The fitting is then lined by injecting theliner material into the region defined by the interior surface of thefitting and the die(s).

Moreover, the subject invention has been described such that the pipesegment in question is pre-lined, whereupon a portion of the pre-linedpipe segment is subsequently removed to expose a portion of thepolymeric liner and to create the first and second section ends.However, in the case of looselined, sliplined and interference fit pipesegments, the liner may be pulled through the pipe section such that itextends therefrom, without sacrificing the benefits of the subjectinvention.

Other embodiments of the invention described above will be readilyapparent to those having skill in the art. Accordingly, the scope of theinvention shall be limited only by the claims appended hereto.

We claim:
 1. In a flangeless pipe joint for polymer-lined pipe having(a)a first section of pipe (100) having a first section end (120), saidfirst section of pipe being lined with a first polymeric liner (110)having a first liner end (130) extending from said first section end;(b) a second section of pipe (100') having a second section end (120'),said second section of pipe being lined with a second polymeric liner(110') having a second liner end (130') extending from said secondsection end; (c) joining means (140) for joining the first liner end tothe second liner end, said joining means serving to restrain linearmovement of said first polymeric liner and said second polymeric liner;and (d) an annular metallic coupling (150) for joining said firstsection end and said second section end, characterized in that theannular coupling comprises a mechanical coupling retained on said firstsection of pipe and said second section of pipe by compressive force. 2.The flangeless pipe joint of claim 1 wherein said polymeric liner is apolymer selected from the group consisting of polyvinylidene fluoride,polypropylene, polyvinylidene chloride, polytetrafluoroethylene,perfluoroalkoxy copolymer, and fluorinated ethylene-propylene copolymer.3. The flangeless pipe joint of claim 1, wherein the first polymericliner is positioned in the first section of pipe by a method selectedfrom the group consisting of slip-lined, interference fit, swaged, andloose-lined and the second polymeric liner is positioned in the secondsection of pipe by a method selected from the group consisting ofslip-lined, interference fit, swaged, and loose-lined.
 4. The flangelesspipe joint of claim 1, wherein said joining means comprises a weld bead.5. The flangeless pipe joint of claim 1, wherein the first joining meanscomprises a polymeric coupling inserted between the first polymericliner end and the second polymeric liner end, the polymeric couplingfurther comprising an annular sleeve which wraps around the firstpolymer liner and the second polymeric liner.
 6. The flangeless pipejoint of claim 1, further comprising:(e) a secondarily contained leakdetection zone.
 7. The flangeless pipe joint of claim 6, wherein saidsecondarily contained leak detection zone comprises an annular gapbetween said joining means of step (c) and said annular coupling.
 8. Theflangeless pipe joint of claim 6, further comprising:(f) meansoperationally connected to said secondarily contained leak detectionzone to permit detection of leaks in said joining means of step (c). 9.A process for preparing a flangeless pipe joint for polymer-lined pipecomprising:(a) providing a first section of pipe (100) lined with afirst polymeric liner (110) having a first liner end (130) and a secondsection of pipe (100') lined with a second polymeric liner (110') havinga second liner end (130'); (b) removing a portion of said first sectionto expose an annular portion of said first polymeric liner and to form amodified first section having a first section end; (c) removing aportion of said second section to expose an annular portion of saidsecond polymeric liner and to form a modified second section having asecond section end; (d) joining said first liner end and said secondliner end with joining means (140), said joining means serving torestrain linear movement of said first polymeric liner and said secondpolymeric liner; and (e) providing an annular metallic coupling (150) tojoin said first section end and said second section end wherein theannular coupling comprises a mechanical coupling which is compressedonto said first section of pipe and said section of pipe such that saidfirst section of pipe and said second section of pipe are decreased indiameter at the points of said compressing.
 10. The process of claim 9,wherein the first or the second polymeric liner is a polymer selectedfrom the group consisting of polyvinylidene fluoride, polypropylene,polyvinylidene chloride, polytetrafluoroethylene, perfluoroalkoxycopolymer, and fluorinated ethylene-propylene copolymer.
 11. The processof claim 9, wherein the first polymeric liner is positioned in thesecond section of pipe by a method selected from the group consisting ofslip-lined, interference fit, swaged, or loose-lined into the firstsection of pipe and the second polymeric liner is slip-lined,interference fit, swaged, and loose-lined.
 12. The process of claim 9,wherein said joining comprises welding or fusing said first polymericliner end to said second polymeric liner end.
 13. The process of claim9, wherein said joining comprises inserting a polymeric coupling betweensaid first polymeric liner end and said second polymeric liner end, saidpolymeric coupling further comprising an annular sleeve which wrapsaround said first polymer liner and said second polymeric liner, andjoining said polymeric coupling to said first polymeric liner and saidsecond polymeric liner.
 14. The process of claim 13, wherein saidpolymeric coupling is joined to said first polymeric liner and saidsecond polymeric liner by socket welding, adhesives, solvent welding,and electrofusion.
 15. The process of claim 9, wherein a secondarilycontained leak detection zone is formed between said joining means andsaid annular coupling.
 16. The process of claim 15, wherein saidsecondarily contained leak detection zone comprises an annular gapbetween said joining means of step (d) and said annular coupling. 17.The process of claim 15, further comprising:(f) providing meansoperationally connected to said secondarily contained leak detectionzone to permit detection of leaks in said joining means of step (d).